This invention relates, generally, to communication networkshaving radio frequency (xe2x80x9cRFxe2x80x9d) amplifiers, and, more particularly, to connections at network nodes.
As broadband networks continue to move from the experimental realm to the order of the day for network and service providers, the competition-driven need for providers to reduce costs of implementation increases proportionally. Community Antenna Television (xe2x80x9cCATVxe2x80x9d) has traditionally relied on metallic coaxial (xe2x80x9ccoaxxe2x80x9d) cabling to deliver video signals. The conductors that transport the signals through the network may be typically connected at various points within the network, such as head ends, or central offices, nodes and subscriber premise equipment (xe2x80x9cSPExe2x80x9d) devices. The conductors are typically connected at the various types of equipment with connectors that are typically designed to minimize signal loss and to have impedance that matches that of the conductor(s) being connected.
The nodes may include electrical devices that are located outdoors and may be aerially hung from a conductor strand. Whether a node is mounted inside a cabinet affixed to the ground, or installed aerially, a technician typically installs a stinger, a device known in the art for providing an RF connection through a penetration into a housing. The stinger may comprise a hollow metallic shell threaded on the outside, a center conductor and a dielectric interposed between the conductor and the inner surface of the shell. The center conductor projects axially from the stinger such that the device resembles a bee stinger, hence the name. There are various types and styles of stingers known in the art, some designed for lab testing and some designed for field-use. In a lab-test style stinger, the end opposing the projecting conductor typically has a RF terminal. The field-use stinger typically has a mechanism for capturing and transferring electrical signals to the shield and conductor of a coaxial cable. The stinger is threaded into the node housing penetration, which is typically threaded to receive the stinger. When the stinger is in the installed position, the conductor projection into the node housing is guided into a predetermined position. The stinger conductor is guided by a guide device that may include a narrow channel to locate the conductor such that the nail head of a threaded seizure connector device may contact the center conductor when the seizure connector is screwed into place towards the guide, the axis of the seizure connector being perpendicular to the stinger conductor. Moreover, the seizure connector is typically screwed into place with a predetermined torque, the torque value determined to cause the center conductor to be xe2x80x9cseized,xe2x80x9d or clamped, between the nail head and a metallic button that is located on the surface of the guide device underneath the center conductor.
To guide an RF signal from the stinger conductor through the seizure connector, the nail head penetrates the seizure connector through a dielectric device and terminates with a conducting pin inside a barrel defined by the seizure connector. This forms the male end of an RF connector such that the center conductor penetrates a matching female RF connector affixed to an amplifier assembly that houses node-processing circuitry. Although this arrangement provides acceptable transfer of RF signal power into or out of a node, the process of installing a node or performing maintenance is cumbersome because the stinger must be installed before the seizure connector is screwed into place using a torque wrench.
The seizure connector is screwed into place before the amplifier is located within the housing and the connection between the network conductor and the node circuitry is made. Furthermore, if the torque value for installing the seizure connector is exceeded, the stinger center conductor may be deformed, possibly causing degradation of the transfer of the RF signal power from the stinger to the seizure connector. On the other hand, if the torque value is too low, the connection between the nail head of the seizure connector and the stinger conductor may not be sound, thus resulting in poor signal power transfer as well. In addition, even if the torque applied in installing the seizure connector is proper, the nail head surface, as well as the stinger conductor, may nevertheless become deformed. This is because the nail head is turning against the stationary stinger conductor as the force imparted to the conductor is increasing, thus gouging the contact surfaces, which may result in decreased transfer of signal power at RF signal frequencies.
To replace a stinger or remove a node, especially a node that is aerially hung from a strand, the amplifier, which may be secured into the node with a plurality of screws or other fasteners known in the art, must be removed. This typically requires opening the node housing, which may typically be a hinged, clamshell housing fastened with screws or other known fasteners. After the amplifier has been removed from the housing, the seizure connector is unscrewed so that the seizing, or clamping force, exerted by the seizure connector nail head towards stinger conductor and opposed by the guide button, is relieved so that the stinger can be unscrewed from the node housing.
Thus, there is a need for a method and system that reduces the number of steps for installing or removing a stinger from a node, thus resulting in a less cumbersome method of installing a node in a network. Furthermore, there is a need for a method and system for providing an even and constant exertion of force for maintaining contact between the stinger conductor and the nail head. There is also a need for a method and system for minimizing damage that may occur to the stinger conductor and nail head contact surface areas due to gouging as the seizure connector is screwed towards the stinger conductor.
An objective of the invention is to provide a simplified method and system for seizing a stinger center conductor between a force exerting means and the end of a conducting pin, the pin being part of a connector means having an axis perpendicular to the axis of the center conductor, to facilitate transferring of electrical energy from the stinger to the connector.
It is another objective to provide a means of exerting said for such that a unique torque is not specified for providing contact between the stinger conductor and the pin. Furthermore, it is an object to provide a method and system for exerting said force in a substantially constant amount regardless of slight tolerance variations in the alignment among the stinger center conductor, the force exerting means and the pin of the connector.
It is yet another object to provide a method and system for exerting a force on the stinger conductor, thereby bringing it into contact with the center pin of the connector, but without gouging the surfaces of contact of the pin or the stinger conductor.
Generally described is a system for connecting an RF node into a network comprising means for electrically interfacing with a stinger signal conductor and means for exerting a resilient force opposing the interfacing means, the exerted force maintaining the stinger conductor in positive contact with the interface means. The exerting means may include a non-conductive plunger having a distal face for applying the exerted force towards the electrical interface means. A transition between the distal face and a side face of the plunger may be chamfered. The interface means may include a conductor button, also referred to as a nail head, for contacting the stinger conductor at a contact area, the button being at the end of a pin that functions as the center conductor through a dielectric.
The exerting means may be rigidly installed into a housing, the housing defining mounting holes for the exerting means and the stinger such that an axis of the exerting means and the interface means are coaxial. The interface means may be rigidly mounted and located to a circuit amplifier such that when the amplifier is installed into the housing, the stinger conductor may be interposed between the exerting means and the electrical interface means at a right angle to the axis of the opposing interface and exerting means when the stinger is installed into the housing.
Also generally described is a method for installing a node comprising the steps of rigidly attaching at a predetermined location on a circuit board of an amplifier an RF connector having an electrical interface, installing a stinger into a housing of the node and installing a force exerting means for resiliently forcing the center conductor of the stinger against the electrical interface of the RF connector. The amplifier may also be installed into the node housing before or after the exerting means has been installed.
A process to remove the node comprises the steps of partially removing the exerting means from the housing to reduce or remove the force exerted against the stinger conductor and removing the stinger from the housing. The amplifier may also be removed from the node housing if the exerting means has not been removed.